#include<stdio.h>
#include<math.h>
int main() 
{
    int a, b, count = 0;
    scanf("%d %d", &a, &b);
    for (int i = a; i <= b; i++) {
        int val = i, sum = 0;
        while (val) {
            sum += val % 10;
            val /= 10;
        }
        if (sum % 5 == 0) count++;
    }
    printf("%d", count);
    return 0;
}
